I am now just imagining that logic in my server... Apparently Fargo's Mutant has some 3 billion hp or w/e. That'd be a lot of damagei'm never a fan of that Percent damage and for obvious reasons people can take advantage of it say in multiplayer people decided to go all ranger
and use that 8% health to their advantage to a boss....(8 x Number of players) .....yea bad idea!
Though I have noticed that (with mods like Calamity) some bosses actually have damage gates. Currently, my damage output on things like training dummies with my Summoner build get me close to 80k DPS. On the bosses like Ravager (Calamity boss) and Moon Lord I am getting around 9 - 13k. So I am unsure how % damage is technically used in these cases.